Well, I was out on my Seven this weekend and I have to admit that for me it is a much nicer frame than my CF race frame. I am not too sure how to describe it other than the Seven works well with my style of riding where I find the CF frame to somewhat fight my inputs.

Anyways, without getting to deep into it I am thinking of using the Seven as my new race bike but as such I would love to have my SRM and other race bits on there. To make that happen I'd need to swap out the BB shell (not sure if that's possible yet) and modify the HT (Seven will do this mod). For those of you that have done such modifications to your frames has there been a noticeable difference? I don't want to invest a big chunk of change in my frame and then have it feel different than it currently does.

I had Seven swap a 1 inch headtube for a 1, 1/18 about 10 years ago on an Axiom that I no longer own. They did a fantastic job, and you wouldn't know it had ever been done.

So, in terms of 'can it be done'? Yes. In terms of 'are they good at it'? Yes.

Now the more tricky question 'will it make a difference'? Honestly not.

I had my 1 inch swapped because it was getting hard to buy forks. In terms of the performance advantage of a 44mm head tube and BB30 bottom bracket vs 1, 1/8 and standard English threaded, I can comment from experience.

I own a Seven Axiom SLX with standard English threaded bb and 1, 1/8 head tube. I have a Colnago Master with Italian threaded bb and a 1 inch head tube. I also have a Moots RSL with a press fit BB30 bb and a 44mm headtube.

Let's take the bb first:

Honestly, other than the aesthetics of the Moots looking more modern, the oversized BB doesn't make a difference. It doesn't feel noticeably stiffer because I run the identical Super Record chainsets on all 3 bikes. So, the axles and bb bearings are identical in all 3 bikes. Comparing it to the Colnago is difficult because it has a super stiff cast bb shell. So, actually this isn't quite 'apples with apples' as despite the smaller diameter of the tubes butting up against the bb, and the inherent nature of steel vs ti, the Colnago is still stiffer than the Moots. I had the Seven built stiff, and as you know, Seven can make ti feel as stiff or compliant as you want. Nevertheless, I can feel only a tiny (and possibly only psychological) difference in bb and drive stiffness between the 2. Blindfolded, I couldn't tell the difference.

In terms of press fit BB30, I have not experienced any problem with the Campagnolo press fit BB30 UT cups, unlike some people. I used plenty of molybed grease during installation, and it has been quiet and movement free.

The advantage of the larger bb is often to allow a bigger down tube and stays to attach to it in order to increase stiffness. Now, first question is do you subscribe to the 'stiffer is better' philosophy? There's a whole other discussion right there, but if you do, ti probably wasn't the right choice in the first place. Let's assume you were drawn to ti because of its comfort. Since having a new bb retro-fitted won't enable Seven to install bigger stays or down tube, you won't get most of the benefits anyway.

Since you want to fit an SRM which I am guessing is BB30, then this would be the only reason to swap.

Now the headtube:

Is tapered 44mm stiffer than 1, 1/8 or even 1 inch? Again, not noticeably. Given the length of most headtubes, you won't notice much of a difference in the frame itself. Much like the intersection of a BB30 and the downtube, a 44mm headtube allows for a larger (and therefore stiffer) interface with your forks. But again, is stiffer always better? And is a 1.5 inch fork crown really that much stiffer than a well made 1, 1/8 fork crown anyway?

Much like my decision to replace 1 inch with 1, 1/8 all those years ago, it has a lot to do with future proofing your bike. Non tapered forks will become increasingly difficult to get hold of at some point, and the handmade, metal bike market does seem to be transitioning towards a 44mm standard to allow for either tapered or internal headsets and forks.

So ultimately, Seven will do a great job for you. In order of priority, I would probably change the headtube (but be aware of the geometry changes necessitated by either a tapered external headset cup, or a non-tapered internal headset cup), but I probably wouldn't bother with the bb. On a new build, yes because it can facilitate a larger downtube and stays. As a retro-fit, the risk of creaking and problems with adapters probably makes it better to save your money and invest in a better chainset and bb instead.

If I may ask a supplementary question - I have a Van Nicholas Astraeus. Would it be possible to adapt this for disc brake use, as and when (and if...) they become standard in the future? I'm UK based, so not sure who'd do the work, perhaps Enigma?

The BB30 would only be to facilitate the SiSL SRM, as I am not big on the whole stiffness issue or believe that Ti bikes are noodles, especially in my size. I wouldn't change the HT to 44, but actually get it shortened. When I ordered the bike 10 years ago I had a 1cm extension added to the HT, as well as 2cm of spacers. I now ride a much lower position than is attainable on the Seven with a standard headset and am currently running an AER. I am not a big fan of the setup, maintenance, or durability. If I were to make this my race bike instead of my CF bike then it would be logging lots of miles and see inclement weather. Therefore, I think it would be best to remove the 1cm of extension and run a normal headset that will last. In addition, I am not a big fan of fat HTs on small tube bikes. Therefore, aesthetically I would prefer to keep the 1 1/8 HT. Again, thank you for the detailed response it puts my mind at ease in having the modifications made to the frame.

edit: added my thoughts about looks.

Last edited by Stalkan on Mon Feb 11, 2013 8:56 pm, edited 1 time in total.

There's a big difference involved in replacing a head tube compared to a BB shell. It may just about be possible to do , but the price is going to be prohibitively high as you're effectivley having to re-mitre 4 tubes to handle a new and wider bb shell, then re-do 4 welds, then get the alignment done right. It'd probably be cheaper to buy a new frame.

$775 for a HT with reduced height or $1025 for the 44mm HT, and $750 for the BB30 conversion. Since my Alta is no longer available the only other model with the same tube-set is the Axiom SLX and it is $4200 retail. Obviously, all those prices are subject to change.

I know 7s are premium frames and they do good work but can't the HT just be shortened (cut off)? Maybe its butted or something but that seems at least possible. Also I don't really like the look of neg rise stems, but its a much cheaper solution to your problem.

Thats plausible but I am going to trust Seven in this situation. The other problem lies in the steerer would be too short on a standard headset. For instance the 110 has an upper stack height of 16mm whereas the AER is just under 8mm (lower stack is the same). There are no spacers above or below the stem to facilitate an increase in headset stack height.

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